1. Field of the Invention
The present invention relates to a driving apparatus, and an industrial instrument and an exposure apparatus, each including the driving apparatus, and a device manufacturing method of manufacturing a device using the exposure apparatus.
2. Description of the Related Art
An exposure apparatus for manufacturing a device, such as a semiconductor device or a liquid crystal device, is one example of industrial instruments. The exposure apparatus is constantly required to increase the throughput in order to improve the productivity. This makes it indispensible to drive the wafer stage and the reticle stage at higher velocities.
Linear motors are generally used as actuators that drive the wafer stage and the reticle stage. High-velocity driving requires increasing the acceleration of the wafer stage and the reticle stage, so a large thrust must be produced by, e.g., increasing an electrical current supplied to the linear motors or combining a plurality of linear motors to constitute one actuator. To meet these demands, linear motor driving circuits for driving the wafer stage and the reticle stage tend to have large-capacity outputs, and the number of outputs tends to increase. However, these tendencies lead to an increase in the heating values of the driving circuits and high-voltage power supplies for the driving circuits.
If heat generated by an industrial instrument, such as an exposure apparatus used in a temperature-controlled clean room, is directly exhausted, a heavy load is imposed on the clean room equipment. To avoid this situation, heat generated by, e.g., the driving circuits and power supplies, can be generally collected at a single site and exhausted outside the clean room through an exhaust duct (see Japanese Patent Laid-Open No. 2005-268546).
However, as the total heating value increases, the sectional area of the exhaust duct for exhausting the heat to the outside of the clean room must be increased. This reduces the effective space of the clean room. In addition, the scheme that exhausts heat to the outside of the clean room through the duct requires huge equipment.
In the clean room equipment, the sectional area of the exhaust duct and the flow rate of air supplied to it are generally determined, assuming the severest of conditions. However, all exposure apparatuses are less likely to always operate with maximum heating values, and their heating values upon driving the wafer stage and the reticle stage fluctuate depending on exposure conditions, such as the exposure shot size and the exposure pattern. If, for example, the exposure shot size is relatively large, the number of times of exposure per substrate is less than that if it is relatively small. In other words, the numbers of times of driving of the wafer stage and the reticle stage can be saved accordingly, resulting in a decrease in total heating value. In an extreme example, if the exposure apparatus is stopped due, e.g., to interlock, the wafer stage and the reticle stage are, in turn, stopped and, therefore, the heating values of the driving circuits become nearly zero. Considering these facts, the clean room equipment often continuously supplies more power than is necessary.